Phase Change Matters

The award-winning Phase Change Matters blog tracks the latest news and research on phase change materials and thermal energy storage. E-mail tips and comments to Ben Welter, communications director at Entropy Solutions. Follow the blog on Twitter at @PureTemp. Subscribe to the weekly PCM newsletter. Or join the discussion on LinkedIn.

The PCM modeling research, conducted at University of Manitoba, also found a reduction in "discomfort hours" from 10 percent to 29 percent, depending on the zone and PCM type.

The researchers set out to investigate the feasibility of integrating PCMs within a suspended ceiling using the hysteresis method in EnergyPlus 8.9. The hysteresis effect, wherein a PCM has different melting/freezing temperature curves, complicates the simulation of PCM use in buildings. The EnergyPlus modeling software was updated in 2017 to include the effect of hysteresis.

Minneapolis-based PureTemp LLC provided the researchers with the thermo-physical properties of PCMs required for modeling in EnergyPlus. Five types of PCMs, namely PCM20 (PureTemp 20), PCM21, PCM22, PCM23 (PureTemp 23), and PCM24, were tested and analyzed. The melting and freezing temperatures of the five PCMs fall within the thermal comfort range and operation of the HVAC system of the building the researchers chose as a case study: the University of Manitoba's new Stanley Pauley Engineering Building.

The number of each PCM represents the material's peak melting temperature in degrees Celsius. The theoretical properties of PCM21, PCM22 and PCM24 were derived from the actual properties of PureTemp 20, PureTemp 23 and PureTemp 25.

One of the study's authors, Dr. Miroslava Kavgic, right, is an assistant professor of civil engineering at the university. She answered questions about the research by email.

Q: What do you think is the most important finding, as far as impact on manufacturers of PCMs and PCM products?

A:"The findings of our research study suggest a promising future for the applications of PCMs in buildings located in cold climates. Furthermore, our study showed that in addition to already proven cooling energy-saving potential, PCMs can be very efficient in reducing heating energy demand. As a result, the findings from our study can increase application of PCMs in buildings located in the dominant heating climates, and therefore increase the demand for these unique building materials. We also hope that higher demand for PCMs will bring down their price which currently hinders the more extensive application of PCMs in areas with the lower energy prices such as Manitoba."

Q: Why did you choose to use PureTemp data? Was there a preference to use a biobased PCM? Or was data on other products hard to obtain?

EnergyPlus PCM model, enthalpy-temperature method

A:"PureTemp shares valuable thermo-physical properties of its PCM products on its website. Furthermore, upon our request PureTemp provided additional information required for the modeling of PCMs in EnergyPlus using hysteresis method. PureTemp also provides other useful information related to various applications and experimental testing of PCMs. Finally, PureTemp’s PCM products are produced from agricultural sources, and they are readily biodegradable and non-toxic. These positive characteristics of the PureTemp’s PCM products can enable the development of environmentally friendly solutions that can significantly reduce buildings’ energy consumption while improving their indoor thermal comfort."

Q: Given the impact of a PCMs hysteresis the final simulation results, is there a standard you’d like the industry to establish for consistent data from the PCM manufacturers?

EnergyPlus PCM model, hysteresis method

A:"Consistent data from the PCM manufacturers would increase confidence in the modeling results, and this applies to both hysteresis and temperature-enthalpy methods. Moreover, the consistent PCM properties could also be beneficial for the manufacturers as they will allow the end-user to test multiple PCMs and purchase several different materials for real-world implementation. This is particularly important considering the need for numerical analysis before the real-world implementation due to both complex behavior of PCMs and their relatively high price. The sensitivity analysis of the hysteresis input parameters suggests that manufacturers should pay partial attention to the parameters that have high impact on the simulation results."

Q: For future work, is there interest in comparing the same PCM measured with different methods, such as T-history and DSC?

A:"The t-history method is relatively inexpensive and straightforward to measure the phase-change enthalpy of PCM products using considerably larger sample sizes compared to DSC, and therefore for non-uniform PCMs it is a good testing alternative to DSC."

Table 3. Thermo-physical properties of the tested PCM:

Hysteresis properties

PCM20

PCM21

PCM22

PCM23

PCM24

Latent heat during the entire phase change process (J/kg)

171,000

189,000

208,000

227,000

207,000

Peak melting temperature (°C)

20

21

22

23

24

Peak freezing temperature (°C)

18

19

20

21

22

Liquid-state thermal conductivity (W/(m∙K))

0.14

0.143

0.146

0.15

0.15

Solid-state thermal conductivity (W/(m∙K))

0.23

0.236

0.243

0.25

0.25

Liquid-state density (kg/m3)

680

730

780

830

840

Solid-state density (kg/m3)

950

936

923

910

930

Liquid-state specific heat (J/(kg∙K))

2150

2096

2043

1990

2140

Solid-state specific heat (J/(kg∙K))

2070

1993

1916

1840

1915

The full version of the paper is available here through the end of September 2019:

• Sonoco ThermoSafe has announced the creation of a passive, temperature-controlled container that will be manufactured by AEROTUF of Charleston, S.C. The Pegasus ULD container will use AEROTUF’s patented AeroTHERM composite material technology, along with a gelled phase change material. "The Pegasus ULD will ultimately provide 2-8, CRT, and frozen temperature ranges depending on the PCM used for durations up to and exceeding five days," said Ben VanderPlas, manager of Engineering and Product Management at ThermoSafe, which is based in Arlington Heights, Ill. A launch date for the product has not been announced.

• The Chinese rail company that worked with the UK's University of Birmingham last year to develop a prototype of PCM-based freight container is bringing the concept to market. Hebei-based transport business CRRC Shijiazhuangsold 49 of the containers to a manufacturer in China this month. The low-emissions freight containers keep payloads cold without the need for fuel-generated refrigeration. "We are delighted to see our cold storage technologies start to make the commercial market," said Yulong Ding, director of the Birmingham Centre for Energy Storage. "We are working with our partners to extend the cold storage technologies to more applications."

• Here's a co-branding opportunity for a PCM manufacturer with a taste for hops: Lagunitas Brewing Co. of Petaluma, Calif., has introduced Phase Change, "an unfiltered, wet-hop ale packed full of lupulin-drenched Simcoe, Citra & Mosaic hops." The brewer describes the beer as "somewhere between a solid and a liquid... a Phase Change of sorts."

• More than 170 speakers are lined up for the 14th International Conference on Advanced Building Skins, to be held Oct. 28-29 in Bern, Switzerland. The Japanese architect and Pritzker laureate Shigeru Ban will deliver the keynote address. Thomas Friedrich of Innogration GmbH, Germany, will discuss "collection of thermal energy from the façade" and "decentralized PCM storage elements for saving thermal energy." Damien Mathis of Ai Environnement, Paris, will give a presentation on the "thermal performance of engineered wood flooring impregnated with phase-change materials." The registration fee is 680 euros and includes the conference documentation as well as meals during both days. Participants who register by Aug. 30 will receive a 10 percent discount.

"A delivery device includes a collar device for wearing on an animal, a dosing probe disposed on the collar device for delivering a substance therefrom, an actuator configured to deliver the substance from the dosing probe through an opening formed in the dosing probe, a controller in communication with the actuator and configured to control delivery of the substance from the dosing probe, and a sensor in communication with the controller and configured to sense that the collar device is touching fur or skin of the animal and the dosing probe is directed towards fur or skin of the animal."

"The present invention is directed toward an article of apparel effective to regulate the temperature of the wearer. In an embodiment, the article of apparel includes a base textile with a thermal regulation membrane. The thermal regulation membrane contains a plurality of system-reactive components selectively engaged heat and/or moisture. In an embodiment, the printed coating includes a cooling agent, a phase change material, and a heat dissipation material. In operation, the article of apparel is effective to delay/diminish the rise in skin temperature (compared to a garment lacking the membrane), increasing wearer comfort."

"Disclosed is a heat exchange device including a first thermally conductive tube that is hollow over its length, a second thermally conductive tube that is hollow over its length, and including a thermally conductive fin, in which the fin extends lengthwise along the first tube, the fin extends lengthwise along the second tube and the fin extends width-wise between the first tube and the second tube. ... The invention is open to industrial application or useful in the field of heat accumulators, transferring heat between two phase change materials and in particular for storing energy in the form of ice from freshwater or saltwater or brackish water."

• Innovate UK’s Knowledge Transfer Partnership has awarded funding to a joint effort by AMP Clean Energy and the University of Birmingham to develop a thermal energy storage system. The system will incorporate phase change material developed by the university for use in AMP’s Urban Reserve flexible electricity generation plants, which will turn waste heat into electricity. The amount of funding was not disclosed.

• Australian start-up 1414 Degrees has announced a joint project with Nectar Farms to test “SmartFarm” applications of 1414's technology, which stores electricity as thermal energy by heating and melting containers full of silicon.

"A method for the production of a temperature regulating polyurethane gel composition and corresponding articles includes fatty acid esters as a phase change material (PCM) directly incorporated in the fluid phase of a polyurethane gel without encapsulation. The liquid or melted PCM is solved in the polyol component of the gel and is able to crystallize and melt within the gel structure reversibly. The polyurethane gels are under-crosslinked and include an at least nominal three functional ethylene oxide-comprising alkylene oxide polyether polyol with 0 to 40% EO and an isocyanate with an effective functionality of from 1.5 to 3.5. The gels are useful in articles where the gel can be positioned close to the human body for temperature regulating purposes, and especially to improve the sleeping comfort of a resting person."

"An eco-smart panel is described comprising a a solar thermal panel, a phase change material, a metal foil layer, and a structural frame constructed of materials including wood studs, gypsum, or fiberglass-reinforced concrete. The materials may be variously configured to create modular systems for fabricating buildings or structures. Eco-smart panels may be utilized to create buildings or structure with enhanced energy efficiency, increased fire resistance, increased flood resistance, and decreased construction cost and time."